View Full Version : Larry Vickers comments on chrome lined barrels vs nitrated barrels
I think most everyone would agree chrome lining is superior with the possible exception of accuracy - major manufacturers like HK and FN still use it which is a clue
Part of the push to methods other than chrome lining is due to environmental restrictions - the good old EPA
Be safe
LAV
I thought it was the other way around that Nitrating processes was what caused enviormental concern, not chrome lining. I believe LWRC uses nitrated barrels.
NiCorr™ surface conversion has proved more lubricious, harder wearing, more heat and corrosion resistant than the hard chrome normally used in the bore. Our barrels can handle 20,000 rounds before replacement, as compared to 6,000-10,000 rounds on a standard M4.-LWRC website
We offer a variety of NiCorr treatments depending on the finish and corrosion resistance required. NiCorr-C leaves a hard, low microfinish, black corrosion resistant surface capable of resisting 360+ hours of accelerated salt spray as tested per ASTM B117. It competes favorably with Chrome and Electroless Nickel Plating. Plating is eliminated: saving cost of plating, transportation time. NiCorr is environmentally benign. -www.syracuseheattreating.com
His claims don't appear to be true.
"The salts used are highly toxic - Disposal of salts are controlled by stringent environmental laws in western countries and has increased the costs involved in using salt baths. This is one of the most significant reasons the process has fallen out of favor in recent decades."
You might want to clean this up. I have no idea who's quotes are who's.
Not all nitriding involves salt baths.
I am NOT saying LV is wrong here but in my case I am skeptic of what anyone says on these threads. I have seen way too much mis-information posted on here even from the resident experts.
I recall once seeing a posting, I believe being said about how all parts were built in house by a certain manufacturer, How their manufacturing and QC was all done in house. I know for a FACT that it was not true. I personally know where those particular parts were being subcontracted and know the very guy in lead of their production. So don't accept everything you read one these sites without due diligence.
Probably one of the reasons I don't post much, prefer to read and ask questions to get topics started or of interest.
JMHO
Robb Jensen
02-25-12, 19:50
I believe what LAV was referring to is processes like Glocks tenifer which has a byproduct of cyanide IIRC. In the Advanced Armorers course Glock stated that US made slides/barrels have a different process which is essentially melonite without that byproduct. Nitro carburizing is what Glock calls the metal treatment done in the U.S. and is done without the large amounts of toxic haz-mat like tenifer.
SomeOtherGuy
02-25-12, 19:52
Not all nitriding involves salt baths.
Exactly, there are other ways of nitriding that are environmentally benign. What I've read suggests that salt bath nitriding generally produces the best surface properties however.
Likewise, some forms of chrome plating are really nasty and others somewhat less so, and in any event it is possible (at expense) to keep things clean enough.
This thread is begging for some Rsilvers comments as he seems to have some firsthand data on the topic.
Robb Jensen
02-25-12, 20:00
From the little I know about meloniting barrels is that it's extremely hard. If small imperfections are in a barrels and aren't smoothed down early in the barrels life or hand lapped they be there forever. I'm thinking of having my new 18" BCM SS410 barrel melonited after 500 rounds. I find that with stainless barrels their very best accuracy is after 300 rounds or so but before 2K rounds depending on how the the barrel is shot.
From the little I know about meloniting barrels is that it's extremely hard. If small imperfections are in a barrels and aren't smoothed down early in the barrels life or hand lapped they be there forever. I'm thinking of having my new 18" BCM SS410 barrel melonited after 500 rounds. I find that with stainless barrels their very best accuracy is after 300 rounds or so but before 2K rounds depending on how the the barrel is shot.
So in your opinion, melonited barrels like those offered by s&w are superior to chrome lined and stainless barrels?
Robb Jensen
02-25-12, 21:02
So in your opinion, melonited barrels like those offered by s&w are superior to chrome lined and stainless barrels?
Some melonited barrels will shoot really well and some don't. If a melonited barrel doesn't shoot well nothing is going to make it shoot well. Good consistent hammer forged chrome lined barrels like FN pretty much ALL shoot very well. Stainless BCM SS410 barrels always shoot well but not as long as heavy chromed hammer forged barrels. Just my dos centavos. This is why I want to be sure my SS410 is shooting very well and THEN meloniting it....
You don't have a concern about the bore dimensions changing from the addition of the nitride?
Who provides this service for small projects?
An Undocumented Worker
02-25-12, 22:14
Nitriding or Ferritic Nitrocarbuerizing does not add to the surface of the steel. It is a conversion process that in simple terms is akin to case hardening a part while at the same time imparting corrosion resistance to carbon steels.
FERRITIC NITROCARBURIZING accomplishes surface treatment of
a part in the ferrite region of the iron-carbon equilibrium diagram (Fig. 1).
As the process takes place in the ferrite region, both nitrogen and carbon
diffuse into the steel surface. The process is categorized as a thermochemi-
cal treatment and is carried out at temperatures between 525 and 650 °C
(975 and 1200 °F); the typical process temperature is approximately 565 °C
(1050 °F). The purpose of the process is to diffuse nitrogen and carbon
atoms into a solid solution of iron, thus entrapping the diffused atoms in the
interstitial lattice spaces in the steel structure (Ref 1).
Process Benefits
Ferritic nitrocarburizing improves the surface characteristics of plain
carbon steels, low-alloy steels, cast irons, and sintered ferrous alloys. As
described in later sections of this chapter, resistance to wear, fatigue, and
corrosion are improved with the introduction of nitrogen and carbon.
Scuffing resistance means the resistance to wear on the metal sur-
face. This is accomplished by changing the nature of the surface com-
pound layer, which is also known as the white layer. The completed
compound layer will form with both epsilon (ε) and gamma prime (γ′)
phases. The dominant ε-phase resists abrasive wear.
Fatigue properties of steel are greatly improved by altering the com-
position of the compound layer. This means that treated steel has greater
resistance to fatigue failure than an untreated steel (Ref 1).
Corrosion Resistance. After ferritic nitrocarburizing, steel parts can
withstand many hours in a salt spray environment, whereas an untreated
plain carbon steel will fail the corrosion test very rapidly.
http://www.google.com/url?sa=t&rct=j&q=salt%20bath%20ferritic%20nitrocarburization%20process&source=web&cd=2&ved=0CDoQFjAB&url=http%3A%2F%2Fwww.yuntaa.com%2FFileManager%2FDownload.aspx%3FContentID%3D4E8136A3B331150EE04400144FB7B71E&ei=frBJT_ntF86Ttwfjje3uAg&usg=AFQjCNHedz-82tIlzaaLVEKssuyfdXWFrg
Read the PDF in the link for a more thorough understanding on the topic.
An Undocumented Worker
02-25-12, 22:17
You don't have a concern about the bore dimensions changing from the addition of the nitride?
Who provides this service for small projects?
You could try contacting HEFUSA for getting a small project nitrocarbuerized. Just keep in mind that most places like to run large batches of stuff, because whether 1 part or hundreds of parts it costs them pretty much the same to run one batch through the process.
Here is another link that explains the process a bit differently, a good read.
http://domino-69.prominic.net/A55B6F/nitromet/nitromet.nsf/a615da0219b54b79852571cb006bc9d2/d5e108115987d71c862572bc007000f7/$FILE/Nitromet%20Liquid%20Ferritic%20Nitrocarburizing.pdf
An Undocumented Worker
02-25-12, 22:33
And here is a link detailing the QPQ process of ferritic nitrocarbuerization.
http://www.finishing.com/kolene/qpq/
The Kolene QPQ(SM) Process is an adjunct to Kolene Corporation's salt bath ferritic nitrocarburizing (SBN(TM)) treatment called Nu-Tride(R), whereby a mechanical polish and post salt bath oxidative treatment are provided to the nitrocarburized surface. This unique combination of salt bath treatments with intermediate surface finishing, produces a significant increase in corrosion protection while maintaining all the engineering properties initially developed through the SBN process. Additionally, the Kolene QPQ Process provides a cosmetically appealing black surface on the treated component.
Process
The term Kolene "QPQ" is based on a sequence of process events that occur directly following the nitrocarburizing cycle. Referring to the time-temperature profile in Fig. 1, the development of the Kolene QPQ Process may be followed. It begins with the treating cycle of the nitrocarburizing segment, i.e. pre-heat, Nu-Tride salt, Kolene KQ-5OO salt bath quench (SBQ), which produces a layer of epsilon iron nitride, Fig. 2.
The next step is a mechanical polish of the nitride layer, thus restoring the original surface finish. This may be accomplished by vibratory polishing, lapping, centerless polishing, or by other similar means. Finally, to optimize the corrosion resistance, the component is then reimmersed in the Kolene KQ5OO salt quench bath for 20-30 minutes, rinsed and oil dipped. The resulting sequence of quench-polish-quench operations is thus termed the Kolene QPQ Process and may be expressed generically as SBN/SBQ/polish/SBQ.
And here is a case study comparing LNC (liquid nitrocarbuerization, aka salt bath nitride) to chrome lining
http://www.nitromet.com/A55B6F/nitromet/nitromet.nsf/a615da0219b54b79852571cb006bc9d2/e12cddaa4d9861b1852571cd00075581/$FILE/Nitromet%20LNC%20with%20a%20Post%20Process%20Enhancement,%20an%20Effective%20Alternative%20to%20Cr%20Plating.pdf
Introduction
Experience has indicated that liquid ferritic nitrocarburizing (LNC), followed by a mechanical polish and
re-oxidation process, has the capability of producing engineering properties on the surfaces of iron
base components not unlike those resulting from Cr plating. This treatment, and its effectiveness in
producing desired engineering surface properties has been reaffirmed through comparative testing and
evaluations, herein described.
Background
The inherent physical characteristics of the surface layers produced by Cr plating and the enhanced
LNC procedure provide similar engineering properties. However, significant differences relate to the
method of producing the layers, and the resulting physical bonding with the base material. Cr plate is
applied electrochemically to the surface of steel producing a deposition coating, a layer as shown in Fig.1.
Whereas, the thermochemical quench, polish, quench process relies on the diffusion of nitrogen
within a solid base material and the subsequent chemical reaction with iron to produce a microstructural
zone of iron nitrides, Fig. 2, a layer that is integral with the base material.
Frictional characteristics of operating surfaces are also of concern when the mating surfaces are both
steel, or perhaps one non-ferrous metal surface, particularly within applications or systems involving
marginal lubrication. Under these circumstances, it is noteworthy that the nitride compound formed at
the surface during the LNC treatment has an inherent lubricity, and accordingly may function as a solid
film lubricant.
An evaluation of the frictional properties of the LNC nitride layer and the Cr plate, mated with a carburized
and hardened steel surface, was made using the Block-on-Ring test, ASTM G-77 (modified). The
results, Fig. 10, disclose a modest advantage of the LNC nitride layer, indicating a slightly lower frictional
coefficient than the Cr plate surface.
Not all nitriding involves salt baths.
http://www.primeaffiliate.com/track/images/22.gif
http://www.canadablackberry.com/imgs/images/2.tod.gif
vicious_cb
02-26-12, 03:01
I think Ill stick with chrome lining until testing proves that nitrocarburizing is superior. Maybe if some reputable lab took a sample of a batch of barrel blanks from the same manufacturer, chrome lined half and nitrocarburized the other half then proceeded to shoot them to failure perhaps then we would have an answer.
NiCorr™ surface conversion has proved more lubricious, harder wearing, more heat and corrosion resistant than the hard chrome normally used in the bore. Our barrels can handle 20,000 rounds before replacement, as compared to 6,000-10,000 rounds on a standard M4.-LWRC website
This is basically an advertisement. Why the hell would I believe any of this? Besides, aren't there examples of chrome lined barrels that have gone 2x that amount of rounds that are still good.
EzGoingKev
02-26-12, 06:57
There is already a multipage thread on here about this topic.
It has lots of info including on who does it.
Robb don’t run too many rounds down it before you decide to have it done!
I have had more than a few barrels done and if given the choice will go out of my way to have it on all future builds. Running it on a few ARs with no indications of accuracy loss but then I started with good SS barrels to begin with.
I have had at least 10 barrels on long range precision rifles done and it’s amazing! My 308 is sitting at almost 2000 rounds and running 155s at 2950 which is smoking hot. Awesome groups all the way to 1000. I clean it near every 500 rounds with just 2-3 patches just because I feel guilty. There really is no reason to clean it. Chamber hasn’t moved and I am sure the Melonite/ BlackNitride is going to extend the barrel life. Two 7mmShort Mags have just been completed so we will really study the chamber and throat wear as the 7WSM will tear up a barrel quick.
I think more and more manufactures are looking at it and will make the switch. Maybe not the big boys but it is less expensive than chrome and produces an outstanding finish as well.
Like I said, in addition to barrels and pistols I have done numerous AR gas blocks, gas tubes, bolts and bolt carriers with no issues and talk about a smooth and clean running system.
Need to get one of these ARs to another LAV school so I can hear those famous words again, "DUDE that’s as wrong as two boys......."
No one on the planet knows more about combat rifles than LAV so if he says chrome is GTG then no doubt it is. But he did say FN and HK not Bushmaster. That’s a clue!
Some melonited barrels will shoot really well and some don't. If a melonited barrel doesn't shoot well nothing is going to make it shoot well. Good consistent hammer forged chrome lined barrels like FN pretty much ALL shoot very well. Stainless always shoot well but not as long as heavy chromed hammer forged barrels. Just my dos centavos. This is why I want to be sure my SS410 is shooting very well and THEN meloniting it....
Robb, Contact Mark Gordon at Short Action Customs http://shortactioncustoms.com/ he has some great experience with this and uses MMI for the work. As I understand, the heat treatment of the part at manufacture being melonited is critical.
Kreiger barrels were used by MMI during testing and they are for certain good to go for this. My 6.5 Kreiger is a virgin, he inspected it and has just sent it off to MMI. I don't know who makes the BCM barrel, I would check into that and consult SAC.
The increased barrel life and velocity is well worth the cost.
well, this guy says 416R is ok, he used a Barlein, which are top notch also.
http://www.youtube.com/watch?v=jiegZyhd5l0
A quote from replies
You are correct, and I tried to explain this point in the article. Once a barrel has been nitrided, the surface hardness is increased to the point that IT IS IMPRACTICAL TO RECHAMBER the barrel with conventional reamers and tools. Basically the steel is so hard it will ruin the tools. On the other hand, if you can get 50% or more accurate life from the barrel, you’ve avoided the need to set-back the barrel in the first place. Once you have a chamber in a nitrided barrel, you can’t rechamber to another cartridge type.
Little more info here
http://blacknitride.com/index.html
http://blacknitride.com/H&M480.mov
Fluidized Bed Nitrocarburization process is also very well thought of by none other than Mike Rock of Rock Creek Barrels. When Mike Rock speaks metallurgy and barrels I LISTEN INTENTLY...
For anyone who has a technical background and would like to read some nice articles simply email me and I'll forward you some Technical Papers.
Thomas M-4
02-26-12, 20:07
Robb, Contact Mark Gordon at Short Action Customs http://shortactioncustoms.com/ he has some great experience with this and uses MMI for the work. As I understand, the heat treatment of the part at manufacture being melonited is critical.
Kreiger barrels were used by MMI during testing and they are for certain good to go for this. My 6.5 Kreiger is a virgin, he inspected it and has just sent it off to MMI. I don't know who makes the BCM barrel, I would check into that and consult SAC.
The increased barrel life and velocity is well worth the cost.
well, this guy says 416R is ok, he used a Barlein, which are top notch also.
http://www.youtube.com/watch?v=jiegZyhd5l0
A quote from replies
Interesting I have a FMP new in white G3 CHF barrel that I have sittiing around for a G-3 clone build. I keep kicking around the idea of having it melonited what would your thoughts be for me having this process done?
Hexavalent Chromium, which is the version generally used for chrome plating, is on the list of verboten materials according to the RoHS initiative foisted upon us by the EU and then accepted by the EPA and various asinine administrations. On that count LAV is correct. Sadly, chrome plating as we know it is gong the way of the dodo bird.
Everyone on here can debate all they want. Scientifically, it has been proven that both chromed and Stainless barrels work just fine. Im not sure why people question why major firearms manufactureres like S&W and even LWRC use a nitriding process on ALL of their barrels. Stop debating about it and just accept that its not the 1970s or even 80s anymore and companies have developed ways of not only making barrels just as hard if not harder, last longer, and have natural lubricity built into them.
Dont believe me....just take your hand and run it over the end of a barrel of a higher end weapon like an Aramlite and then run it over a Smith and Wesson that has been melonite coated. Then come back and tell me that they feel the same. not arguing....but I would hope people would want companies to ffind better and cheaper ways to make better, harder and more accurate barrels that are easier to clean.
My rant is over.
Everyone on here can debate all they want. Scientifically, it has been proven that both chromed and Stainless barrels work just fine. Im not sure why people question why major firearms manufactureres like S&W and even LWRC use a nitriding process on ALL of their barrels. Stop debating about it and just accept that its not the 1970s or even 80s anymore and companies have developed ways of not only making barrels just as hard if not harder, last longer, and have natural lubricity built into them.
Dont believe me... just take your hand and run it over the end of a barrel of a higher end weapon like an Aramlite and then run it over a Smith and Wesson that has been melonite coated. Then come back and tell me that they feel the same. not arguing... but I would hope people would want companies to find better and cheaper ways to make better, harder and more accurate barrels that are easier to clean.
My rant is over.
While I agree that technology marches onward (and using Tuftride/Melonite/Tenifer/SBN there is no way to tell which is harder by simply running your hand over two barrels. What you're feeling is surface roughness differences only.
Personally, I'd like a cold hammer forged, polygonal rifled chromium barrel, cryo it to precipitate carbides, then melonite then hard chrome. But that's just me...
Everyone on here can debate all they want. Scientifically, it has been proven that both chromed and Stainless barrels work just fine. Im not sure why people question why major firearms manufactureres like S&W and even LWRC use a nitriding process on ALL of their barrels. Stop debating about it and just accept that its not the 1970s or even 80s anymore and companies have developed ways of not only making barrels just as hard if not harder, last longer, and have natural lubricity built into them.
Dont believe me....just take your hand and run it over the end of a barrel of a higher end weapon like an Aramlite and then run it over a Smith and Wesson that has been melonite coated. Then come back and tell me that they feel the same. not arguing....but I would hope people would want companies to ffind better and cheaper ways to make better, harder and more accurate barrels that are easier to clean.
My rant is over.
=================================
Huuhhh???
Lot of confusion in your rant.
I question what a lot of AR makers do, especially LWRC.
So, "work just fine" is now a scientific conclusion? So, why change from chrome since it has been scientifically proven...?
And...Armalite (I assume) is now a high-end gun?
How does how it "feels" to my hand make it better or worse....?
But maybe it's just me...
.
Heavy Metal
02-26-12, 22:38
I thought it was the other way around that Nitrating processes was what caused enviormental concern, not chrome lining. I believe LWRC uses nitrated barrels.
His claims don't appear to be true.
"The salts used are highly toxic - Disposal of salts are controlled by stringent environmental laws in western countries and has increased the costs involved in using salt baths. This is one of the most significant reasons the process has fallen out of favor in recent decades."
No, the Chromium plating process produces Hazardous Waste that must be specially disposed of.
Modern Nitriding processes generate little to no Hazmat. I think you are referring to the Eurpoean method using Cyanide Salts.
The plater is charged a fee by the drum to dispose of it by a company liscensed to recieve and dispose of Hazardous Waste. I think sometimes the manufacturer will take it back for a fee and re-process it into new solution.
In the olden days he let it go down the drain to the sewage treatment plant but the plants no longe accept untreated wastestreams due to contamination of their Biosolids.
They can only land-apply if the solids meet or are under a threshold value, otherwise, the sludge is considered Hazwaste and it would be a disposal nightmare from a cost perspective.
Trust me, I know this.
Heavy Metal
02-26-12, 22:41
Hexavalent Chromium, which is the version generally used for chrome plating, is on the list of verboten materials according to the RoHS initiative foisted upon us by the EU and then accepted by the EPA and various asinine administrations. On that count LAV is correct. Sadly, chrome plating as we know it is gong the way of the dodo bird.
It can still be done but if Nitriding has evolved to the point where it works as well or better, it would be crazy to continue Chrome Plating unless an application absolutely demanded it for some niche reason.
Heavy Metal
02-26-12, 22:45
Some melonited barrels will shoot really well and some don't. If a melonited barrel doesn't shoot well nothing is going to make it shoot well. Good consistent hammer forged chrome lined barrels like FN pretty much ALL shoot very well. Stainless BCM SS410 barrels always shoot well but not as long as heavy chromed hammer forged barrels. Just my dos centavos. This is why I want to be sure my SS410 is shooting very well and THEN meloniting it....
Whats the old saying Robb? You can't polish a turd!
If the barrel is inaccurate to begin with, all meloniting will do is ensure it has a very long inaccurate lifespan.
MikeCLeonard
02-27-12, 02:02
Is this the same finish that S&W uses on the M&P pistols? Do they use H&M to do their parts?
I've heard of more than a few M&P's getting rust spots fairly easily on their slides...even newer ones.
Is this the same finish that S&W uses on the M&P pistols? Do they use H&M to do their parts?
I've heard of more than a few M&P's getting rust spots fairly easily on their slides...even newer ones.
I believe S&W makes the slides out of stainless. Melonite tends to reduce the corrosion resistance of most types of SS while still giving it all the other benefits.
Robb Jensen
02-27-12, 06:35
The S&W rusting slide was do to blasting slides with blasting media which contained carbon steel, so they said. Their new pistols don't rust.
Originally Posted by Larry Vickers:
I think most everyone would agree chrome lining is superior with the possible exception of accuracy - major manufacturers like HK and FN still use it which is a clue
With all due respect, I think this time LAV got things other way round and mistook result with cause.
HK and FN live from military procurement. They deliver what military asks for. And military asks for chrome lined bore - puts it in documentation as "copy/paste" all the time. And HK or FN either comply or no-sale. Accuracy requirement set in same documentation is usually on level that good barrel can sustain even with chrome lining, so why should manufacturers fights with this conditions. If military would ask to Hello Kitty Camo, HK and FN would be first to offer it. Our customer, our "Yes, Sir!".
Good example is recent G28 for German Army. They were looking for DMR rifle, but HK417 was not up to accuracy requirements. Among other things chrome lined barrel was one of factors. But HK had civilian rifle, MR308 (now available in US as MR762) that had non-lined barrel. So army asked them to provide it for testing. This time Army was very pleased with accuracy and gave G28 project a GO... and requested chrome lined barrel... in DMR ... :suicide:
Some older (around middle '90s) story of smaller manufacturer and smaller army. Manufacturer developed technology of nitridinng their CHF barrel. All testing showed that those barrels are superior to their chrome lined barrels in every department. Very excited they run to The Army to show results and propose that they will deliver rifles with this new technology as soon as possible. Army "milled" and came with response: "OK, you can use nitriding, but chrome line barrels after that" :suicide: - once again.
Now this factory use nitriding on some civilian products as well as, instead of chrome plating, on gas pistons in assault rifles (Army agreed for that).
Actually, I'd prefer SBN + Hard Chrome on a chromoly barrel (cold hammer forged and cryogenically tempered prior to SBN. But I digress a bit.
FNH has been successful with their cold hammer forged barrel blanks that are then cut for the SPR bolt gun and their "odd" semi-auto rifle. Both are around 1/2 MOA...
Magic_Salad0892
02-27-12, 16:22
I thought carbon steel was better for Nitride treatements, and this was what Glock slides, and barrels were made of?
BTW:
One of the reasons I liked the idea of having a Custom Rock Creek barrel done was because he used 4150CMV, and not SS.
Custom = Ordering a 20'' rifle barrel with M4 feed ramps, send to ADCO, cut to 11.5'' drill gas port to .060'', ''match crown'', polish the barrel.
Then have the Melonite done.
I'm still thinking of having that done.
I thought carbon steel was better for Nitride treatements, and this was what Glock slides, and barrels were made of?
BTW:
One of the reasons I liked the idea of having a Custom Rock Creek barrel done was because he used 4150CMV, and not SS.
Custom = Ordering a 20'' rifle barrel with M4 feed ramps, send to ADCO, cut to 11.5'' drill gas port to .060'', ''match crown'', polish the barrel.
Then have the Melonite done.
I'm still thinking of having that done.
You're correct. Talk to Mike about cryogenics as well. It can be done to the blank prior to machining or done once you have your length and chamber dimensions. The eta-carbides (Fe3C) are what you wish to have precipitate - especially near the surface prior to SBN. He can provide more insight than I as he's probably already done it for customers. The theory (and application in other arenas/applications) already exist...
Magic_Salad0892
02-27-12, 17:25
You're correct. Talk to Mike about cryogenics as well. It can be done to the blank prior to machining or done once you have your length and chamber dimensions. The eta-carbides (Fe3C) are what you wish to have precipitate - especially near the surface prior to SBN. He can provide more insight than I as he's probably already done it for customers. The theory (and application in other arenas/applications) already exist...
Cryogenics?
Sorry, I kinda got lost in your post a little. What benifits would Cryogenics offer?
It only makes sense to do ALL the barrel work first. Trying to chamber after the fact would be really tough and the benifit of extended chamber wear would be gone.
As far a precision rifles go, I have all the barrel work done, test fire and chrono, remove from the action and then get all componets nitrided. Screw it all back together and begin final load development. I shoot most barrels about 20-25 shots and clean before sending them out.
Bolt guns have been Remington 700s, a few Surgeon actions and a Badger. Most all barrels have been Rock 5R SS, maybe one Krieger barrel. No issues and I will continue to do this to any rifle I build from here on out.
Blacknitride/Melonite kicks ass as a finsh!
Interesting I have a FMP new in white G3 CHF barrel that I have sittiing around for a G-3 clone build. I keep kicking around the idea of having it melonited what would your thoughts be for me having this process done?
I really can't answer that other than consult with a good smith like SAC and he would advise. I think it may be cheaper to batch parts vs sending one item. It sure would insure barrel life from the heat you may put on it.
What benifits would Cryogenics offer?
Molecular alignment and less chance of crack type failure along with de-stressing anything built up via the machining process.
Over time and vibration through use the molecules will align anyway, but it would likely take way more bullets than the life of the bore would tolerate.
Getting the molecules more aligned to each other reduces chance of crack failure by virtue of the 'cracks start at sharp edges and corners' physics. More aligned molecules means less edges to start cracks at.
In loose terms its the same thing as using a 'seasoned' iron engine block vs a brand new one that's never been run.
They'll both work, but the seasoned one is going to be less prone to catastrophically fail than the brand new one.
Vibration tables can accomplish simular results as cryo, but that is more suited to whole assemblies rather than singular parts unless done in large batches.
In the sense of a precision barrel, even if not taking failure potential into the equation, better alignment equates to more consistant performance as things won't 'move around' over time since they've already been settled into place.
IOW, more consistant and repeatable harmonics.
Not just "molecular realignment" but carbon steels are BCC (body centered cubic) and molecularly the grains are rather large. Kinda sorta. There is also some amount of austenite (relatively speaking its soft).
Cryogenically treated the structure morphs to a BCT (body centered tetragonal) which means the molecules are much more "compactly" arranged. The grain size decreases and all remaining austenite is converted to martensite (iron carbides).
It also relieves any residual stress that may have been present in the treated steel.
It works best on high carbon content alloys. 4140 is not a high carbon content alloy but the results are still worth the small price.
U will see an increase in toughness, fracture resistance, fatigue strength and wear resistance.
Addendum
BCC vs. BCT
Imagine a cube with molecules on each corner and one in the center. That would be an approximation of Body Centered Cubic molecular lattice structure.
Now imagine a tetrahedron with molecules arranged similarly. More molecules more closely packed. That would approximate Body Centered Tetragonal lattice structure.
Google or use Wikipedia to obtain images (I'm using my iPhone).
So we now have a more densely packed molecular structure - by definition smaller, refined grain size, maximized carbides and no geometry changes if done properly.
I worked with the developer of the process back in the mid-90s (Ed Bush; Cryo-Tech in Hazel Park, MI) and it was eye-opening. I saw Tiger Woods' golf clubs (I didn't know who he was at the time), racing engines (motorcycle, Top Fuel and IMSA GT) and some satellite structural/frame which was larger than I had previously imagined.
When Ed died eventually the company sold the business to 300 Below in Illinois.
Drop temp 1 degree per minute; dwell for 12 to 48 hours; raise temp 1 degree per minute; anneal (400 degrees for one hour and let cool in the oven to room temp. Repeat as necessary (for very thick walled structures - like the satellite structure).
Thanks, Ed. Miss ya, buddy...
Ed asked that I work for him and if the departments and tech specialists I spoke with at Ford had responded favorably to my presentations about the process I would have.
Not just "molecular realignment" but carbon steels are BCC (body centered cubic) and molecularly the grains are rather large. Kinda sorta. There is also some amount of austenite (relatively speaking its soft).
Cryogenically treated the structure morphs to a BCT (body centered tetragonal) which means the molecules are much more "compactly" arranged. The grain size decreases and all remaining austenite is converted to martensite (iron carbides).
It also relieves any residual stress that may have been present in the treated steel.
It works best on high carbon content alloys. 4140 is not a high carbon content alloy but the results are still worth the small price.
U will see an increase in toughness, fracture resistance, fatigue strength and wear resistance.
You were the first person I thought of when I saw this thread. Glad you found it.
SomeOtherGuy
02-28-12, 09:56
Very interesting info, thank you for posting it.
Drop temp 1 degree per minute; dwell for 12 to 48 hours; raise temp 1 degree per minute; anneal (400 degrees for one hour and let cool in the oven to room temp. Repeat as necessary (for very thick walled structures - like the satellite structure).
Does it damage the part or alter its characteristics if it sees operating temperatures greater than 400 degrees?
Very interesting info, thank you for posting it.
Does it damage the part or alter its characteristics if it sees operating temperatures greater than 400 degrees?
No. You'd have to raise the temperature to the recrystallization temperature ( about 0.5 to 0.6 times the melting temp) to have any major concerns. But that's true for an untreated sample as well.
Many infer "magic" and dismiss it but it's merely physics of metallurgy and it works. Some claim an increase in accuracy (I did notice some) but my interest is in durability and it's good for wear resistance (as well as residual stress relief which plays a role in accuracy/repeatability).
Magic_Salad0892
02-29-12, 13:56
No. You'd have to raise the temperature to the recrystallization temperature ( about 0.5 to 0.6 times the melting temp) to have any major concerns. But that's true for an untreated sample as well.
Many infer "magic" and dismiss it but it's merely physics of metallurgy and it works. Some claim an increase in accuracy (I did notice some) but my interest is in durability and it's good for wear resistance (as well as residual stress relief which plays a role in accuracy/repeatability).
Is there anywhere known that somebody could have a barrel cryogenically treated?
What would be the best steel for this?
I thought 4150CMV would be good, but do not know for sure.
.
Is there anywhere known that somebody could have a barrel cryogenically treated?
What would be the best steel for this?
I thought 4150CMV would be good, but do not know for sure.
===========================================
We have a guy locally that has a cryo treating company - Cajun Cryogenics. I was setup at a gun show next to him a while back and we had several long conversations. I know that he does a lot of barrel and other gun part treating. He's a good conscientious fellow that invested in some high-end cryo equipment and does a lot of the local industrial work.
I'm sure Mjolnir knew David from when he lived down here. In case anyone is interested here a link to his business:
Cajun Cryogenics Link (http://www.cajuncryogenics.com/)
.
Magic_Salad0892
02-29-12, 15:28
.
===========================================
We have a guy locally that has a cryo treating company - Cajun Cryogenics. I was setup at a gun show next to him a while back and we had several long conversations. I know that he does a lot of barrel and other gun part treating. He's a good conscientious fellow that invested in some high-end cryo equipment and does a lot of the local industrial work.
I'm sure Mjolnir knew David from when he lived down here. In case anyone is interested here a link to his business:
Cajun Cryogenics Link (http://www.cajuncryogenics.com/)
.
Thank you very much. I may take on a project here.
.
===========================================
We have a guy locally that has a cryo treating company - Cajun Cryogenics. I was setup at a gun show next to him a while back and we had several long conversations. I know that he does a lot of barrel and other gun part treating. He's a good conscientious fellow that invested in some high-end cryo equipment and does a lot of the local industrial work.
I'm sure Mjolnir knew David from when he lived down here. In case anyone is interested here a link to his business:
Cajun Cryogenics Link (http://www.cajuncryogenics.com/)
.
Yes, I did know David and I owe him a Recommendation on LinkedIn.
300 Below should be good to go. Ask to speak with Pete if you can. He worked at Cryo-Tech though I'm not sure if he's still there.
Any alloy is okay but ferrous alloys respond better and the more carbon content the more dramatic the response. However, barrels are definitely classified as Low Carbon Steels. But gains are to be had.
I have a list of suppliers that I put together some years ago that needs revisiting. It lists Nitrocarburization, PVD Coatings and Cryogenics vendors. I'll gladly dig it up and share. It's NOT all-encompassing but it will get u thinking.
Cajun Cryogenics:
David works with Dr. Barron at Louisiana Tech a bit. Dr. Barron was one of the pioneers in the industry. I recall reading an article in Motorcycle Racing magazine back in 1996 on Cryogenics. Dr. Barron was quoted in the article as was Ed Busch. Ed claims to have been one of the original pioneers and I did my research then stopped by to speak with him. He was elated that "a young engineer followed his work and 'knew so much'". Ford has a REMARKABLE technical library... And I gave him a copy of all I had obtained. Massive amounts of research in binders and the parts I mentioned were all over the place. ALL of my toys have been cryoed. My friends in Detroit owned ARGS, Inc. and I worked the shows handing out info and collecting barreled actions for Ed. Anything I had was done for free.
My seeming digression is to say that David was aware of the benefits and was trying to expand his business when I bumped into him at a show. Unfortunately, fate would transplant me from home so I did not get the opportunity to use his services BUT I told him what I've told you here. He will exclusively get all of my business and I recommend him without reservation.
P.S.
Cryogenics works on GLASS and fibers. Ed would treat nuns' habits stating that they wrinkled less. Makes sense as the fibers lose any residual stresses they will have.
I wonder if Leupold, Nightforce, Schmidt & Bender have experimented with there lenses...
For those of us still imagining our perfect carbine barrel, would cryo treatment be done before or after meloniting?
-B
An Undocumented Worker
03-04-12, 21:31
sorry, double post.
An Undocumented Worker
03-04-12, 21:32
For those of us still imagining our perfect carbine barrel, would nitrocarburizing be done before or after meloniting?
-B
Melonite is a tradename for the ferritic nitrocarbuerization process.
Whoops, meant to ask about cryo-treatment and the order a barrel would be cryo'd compared to when it would be nitrocarburized.
-B
An Undocumented Worker
03-04-12, 22:20
Whoops, meant to ask about cryo-treatment and the order a barrel would be cryo'd compared to when it would be nitrocarburized.
-B
From what I've heard from one processor, is that it doesn't really make a difference if you do it before or after processing, as the nitrocarbuerization process doesn't affect the heat treat.
All the plating plating we do at work requires cyanide. Cyanide is used to clean and etch the surface on the molecular level, iirc.
So the whole debate seems moot, based on my current knowledge on the topic.
Honestly when it comes to these types of details in a rifle, major quality manufactures will trend their specifications to benefit shooters. All we need to worry about is buying quality, shooting our rifle and training. But good information nonetheless.
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